Concealed anterograde accessory pathway conduction during the induction of orthodromic reciprocating tachycardia

• Published in: Journal of the American College of Cardiology Vol. 13; no. 2; pp. 391 - 398
• Main Authors: Kou, William H., Morady, Fred, Dick, MacDonald, Nelson, Steven D., Baerman, Jeffrey M.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01-02-1989; Elsevier Science
• Subjects: Adolescent; Adult; Aged; Atrioventricular Node - physiopathology; Biological and medical sciences; Cardiac dysrhythmias; Cardiac Pacing, Artificial; Cardiology. Vascular system; Electrocardiography; Electrophysiology; Female; Heart; Heart Conduction System - physiopathology; Humans; Male; Medical sciences; Neural Pathways - physiopathology; Tachycardia, Supraventricular - physiopathology; Human; Atrium; Instrumental stimulation; Arrhythmia; Cardiovascular disease; Reciprocal rhythm; Wolff Parkinson White syndrome; Concealed conduction
• ISSN: 0735-1097; 1558-3597
• DOI: 10.1016/0735-1097(89)90517-2

The purpose of this study was to determine whether concealed anterograde accessory pathway conduction occurs during the induction of orthodromic tachycardia by an artrial extrastimulus (S2). Sixteen patients with an overt (n = 9) or concealed (n = 7) accessory pathway had inducible orthodromic tachycardia by S2during an atrial drive (S1) cycle length of 500 to 650 ms. A ventricular extrastimulus (S3) was introduced coincident with the His depolarization resulting from S2during the longest S1S2interval that reproducibly induced orthodromic tachycardia. The S1S3interval was decreased in 10 ms steps until S3reached ventricular refractoriness. Retrograde accessory pathway conduction of S3in the presence and absence of S2was compared at the same S1S3intervals.
In the absence of S2there was retrograde accessory pathway conduction after S3in each patient. In the presence of S2, in patients with overt pre-excitation, retrograde accessory pathway conduction after S3was absent in one patient, prolonged in four patients and present only after long S1S3intervals in three patients. Only one patient had unchanged retrograde conduction regardless of the presence or absence of S2. In patients with a concealed accessory pathway, retrograde accessory pathway conduction after S3was absent in five patients and was prolonged in two. Thus, concealed anterograde accessory pathway conduction was present in 15 of 16 patients at the time of orthodromic tachycardia induction.
In conclusion, concealed anterograde accessory pathway conduction occurs in a majority of patients with an overt or a concealed accessory pathway during induction of orthodromic tachycardia by an atrial extrastimulus. In some patients, the initiation of orthodromic tachycardia may depend on a critical interaction between the degree of concealed anterograde accessory pathway conduction and atrioventricular conduction delay after S2.